在片段Android Studio中创建解析器JSON的类

Question

我已经为Google Maps API编写了以下代码。我在地图上添加了标记，但每次我在导航活动中打开“地图”时，所有标记都会消失。除此之外，我有一个RecylerView，当我在onCreate方法中使用它时，它不会从我的API中获取数据。

package com.example.sander.app; 

import android.app.Fragment; 

/** 
* Created by Sander on 4-4-2017. 
*/ 

import android.app.Fragment; 
import android.content.pm.PackageManager; 
import android.location.Address; 
import android.location.Geocoder; 
import android.os.Bundle; 
import android.support.annotation.Nullable; 
import android.support.v4.app.ActivityCompat; 
import android.support.v4.content.ContextCompat; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.Manifest; 

import com.android.volley.Request; 
import com.android.volley.RequestQueue; 
import com.android.volley.Response; 
import com.android.volley.VolleyError; 
import com.android.volley.toolbox.StringRequest; 
import com.android.volley.toolbox.Volley; 
import com.google.android.gms.maps.CameraUpdateFactory; 
import com.google.android.gms.maps.GoogleMap; 
import com.google.android.gms.maps.MapFragment; 
import com.google.android.gms.maps.MapView; 
import com.google.android.gms.maps.MapsInitializer; 
import com.google.android.gms.maps.OnMapReadyCallback; 
import com.google.android.gms.maps.model.BitmapDescriptorFactory; 
import com.google.android.gms.maps.model.LatLng; 
import com.google.android.gms.maps.model.MarkerOptions; 

import org.json.JSONArray; 
import org.json.JSONException; 
import org.json.JSONObject; 

import java.util.ArrayList; 
import java.util.List; 
import java.util.Locale; 


public class GoogleMaps extends Fragment implements OnMapReadyCallback { 
    ArrayList<String> list = new ArrayList<>(); 
    ArrayList<Double> latitude = new ArrayList<>(); 
    ArrayList<Double> longitude = new ArrayList<>(); 
    public GoogleMaps(){ 

    } 
    @Nullable 
    @Override 

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     return inflater.inflate(R.layout.fragment_gmaps, container, false); 
    } 

    @Override 
    public void onViewCreated(View view, Bundle savedInstanceState) { 
     RequestQueue rq = Volley.newRequestQueue(getActivity().getApplicationContext()); 
     String url= "http://test.dontstealmywag.ga/api/parkgarage.php"; 
     StringRequest stringRequest = new StringRequest(Request.Method.GET, url, 
       new Response.Listener<String>() { 
        @Override 
        public void onResponse(String response) { 
         // Do something with the response 
         try{ 
          JSONObject o = new JSONObject(response); 
          JSONArray values=o.getJSONArray("parkgarage"); 
          for (int i=0; i< values.length(); i++) { 
           JSONObject jsonObject = values.getJSONObject(i); 
           list.add(jsonObject.getString("parkgarage_name")); 
           longitude.add(jsonObject.getDouble("langitude")); 
           latitude.add(jsonObject.getDouble("longitude")); 
          } 
         } catch (JSONException ex){} 
        } 
       }, 
       new Response.ErrorListener() { 
        @Override 
        public void onErrorResponse(VolleyError error) { 
         // Handle error 
        } 
       }); 
     rq.add(stringRequest); 
     super.onViewCreated(view, savedInstanceState); 

     MapView mapView = (MapView) view.findViewById(R.id.map); 
     mapView.onCreate(savedInstanceState); 

     mapView.onResume(); // needed to get the map to display immediately 

     try { 
      MapsInitializer.initialize(getActivity().getApplicationContext()); 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 
     mapView.getMapAsync(this); 

    } 

    @Override 
    public void onMapReady(GoogleMap googleMap) { 
     LatLng marker = new LatLng(51.9244201, 4.4777325); 
     for(Integer i = 0; i < list.size(); i++){ 
      googleMap.addMarker(new MarkerOptions().title(list.get(i)).position(new LatLng(longitude.get(i), latitude.get(i)))); 
     } 
     googleMap.addMarker(new MarkerOptions().title("Testing").position(marker)); 
     googleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(marker, 12)); 
     //googleMap.addMarker(new MarkerOptions().title(list.get(1)).position(marker)); 

     if (ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) { 
      return; 
     } 
     googleMap.setMyLocationEnabled(true); 
     googleMap.getUiSettings().setCompassEnabled(true); 
     googleMap.getUiSettings().setMyLocationButtonEnabled(true); 

    } 

    @Override 
    public void onActivityCreated(Bundle savedInstanceState) { 
     super.onActivityCreated(savedInstanceState); 
    } 
} 

我认为问题出在我的JSON解析器代码中。我想把它放在一个单独的课上。任何人都可以帮助我吗？

Answer 1

尝试JsonUtils，你可以解析大部分的数据类型。